I really think that your best bet is to experiment with the "K" (Kelvin) setting in your White Balance menu. As you already know, the cameras allows you to subtly change the temperature of the scene you are shooting by adjusting the white balance setting to things like "cloudy day", "shade", "sunny day", etc. But, these settings are pre-set at the factory to the Kelvin temperatures that Nikon tech's feel approximate each of those conditions. But, sometimes, the colors don't seem correct. As you are experiencing , an example of this is when you try to shoot purple. It more often than not comes out looking more blue, than purple. But, the White Balance Kelvin setting allows you to choose (adjust) the temperature you feel best approximates the color caste of the scene you are shooting. Try this.

Set up you camera on a tripod (so each picture you take is exactly the same scene). Push the "WB" button on the left top of the camera, while rotating the front command dial. You will see the Kelvin numbers change from colder to warmer, and back down to colder, depending on which way you rotate the dial. Take the same scene over and over. Each time you take it, change the Kelvin value and watch how the temperature of each shot goes from cold (blue) to warm. With some practice, you can match the color of the picture you take to closer approximate the color of what your eyes see.